Application Cases

Experiment Title:Application of a Power Amplifier in Forward/Reverse Motion Testing of a Single-Signal-Excited Bending-Bending Hybrid Ultrasonic Motor

Research Field:Ultrasonic motors

Test Objective:To verify the feasibility of the working principle of an ultrasonic motor based on a figure-eight vibration trajectory.

Test Equipment:
• Function/arbitrary waveform generator
• ATA-4051 high-voltage power amplifier
• Two laser displacement sensors
• Laser tachometer

Experiment Overview:
A single-channel special excitation signal (superposition of two sine waves with a 1 : 2 frequency ratio) was used to drive the bending-bending hybrid ultrasonic motor. The motion trajectory of the stator driving foot and the fundamental output characteristics of the prototype were evaluated.

Experimental Procedure

1. Driving-foot trajectory test
   • Two laser displacement sensors were aimed at the top and right surfaces of the driving foot.
   • The waveform generator produced the signal, which was then amplified by the ATA-4051 power amplifier and applied to the motor.
   • After enabling the sensor acquisition, the vibration trajectories were recorded.
   • The phase difference between the two frequency components was swept from 0° to 360° in 15° steps (24 measurements in total).

   
   

2. Output-characteristic test
   • A small pulley was placed at the driving foot and retro-reflective tape was attached to its side. After manually rotating the pulley one revolution, the tachometer was confirmed to count correctly.
   • The signal generator and power amplifier then supplied the excitation signal to the motor. The output speed was measured for different phase differences between the two sinusoidal components.

   
   

Test Results

1. Figure-eight trajectories were obtained at phase differences of 165° and –15°, with opposite motion directions.

2. The proposed motor exhibits less than 4 % difference between forward and reverse output characteristics. When driving a 22 mm-diameter rotor, the maximum no-load speed reached 1373 rpm.

3. The motor achieves bidirectional motion with only a unidirectional excitation signal, utilizes all piezoelectric elements efficiently, and offers high friction-coupling efficiency—features that are attractive for high-reliability aerospace applications.

   
   

Figure : Measured trajectory motion

Figure : Power amplifier mechanical-output test results